1. Field of the Invention
The present invention is related to a cam follower and particularly to a roller follower having a clamp to induce a compression force in a lower pallet portion and/or possibly act as valve guide walls.
2. Description of the Related Art
Roller followers for opening valves in an over head camshaft in an internal combustion engine arrangement are known in the art. FIG. 1 depicts one such known device. The follower of FIG. 1 includes a substantially one-piece U-shaped body having two upstanding sidewalls interconnected by a bottom wall or pallet. A first end of the follower is adapted to receive an end of a lifter post or tappet on which the roller follower can pivot. A second end of the roller follower receives the upper end of a valve stem arrangement. A middle portion of the bottom wall or pallet is cut out to accommodate a roller rotatably disposed between the sidewalls for engaging an overhead cam. The valve stem extends upward from the cylinder head through a coiled compression spring. As the cam rotates, the cam engages the roller to cause the follower to pivot about the lifter/tappet thereby opening and closing the valve as the stem is displaced.
However, the roller follower devices of the prior art are susceptible to fatigue failure at the ends and particularly at the end of the roller follower adjacent the interface with the valve stem.
It is the object of the present invention to improve upon the cam follower designs of the related art and to provide a follower with a clamp to induce a compressive force on the lower pallet thereby increasing fatigue life and stiffness of the follower. Additionally, the side walls of the clamp may extend past the pallet to act as valve guide walls to improve stability during engine operation.
The present invention is directed to cam follower having a clamp disposed on at least one end. A one-piece stamped follower includes two opposing sidewalls interconnected by a lower pallet. A roller is rotatably mounted to and disposed between the sidewalls via needled or journal bearings or other rotatable connection known in the art. A clamp is disposed about an end of the follower to induce compression force in the pallet. The clamp increases the stiffness of the follower and induces compression forces in the pallet thereby increasing fatigue life and allows for long valve guide walls to help the roller finger follower from tipping over during engine assembly operations.